Crystallized Electrolyte Additive for Stable SEI in Li-Ion Batteries
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium ion batteries suffer from poor cycle performance due to the easy precipitation of lithium dendrites on electrode sheets, leading to increased internal resistance and reduced capacity.
Innovation Solution
A preparation method for an electrolyte additive involving the dissolution of picric acid in an organic solvent containing B, F, and N elements, followed by crystallization, which forms a modified electrolyte additive that polymerizes to create a stable SEI film and suppresses lithium dendrite growth during charging and discharging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional electrolyte is used, then the battery can operate, but lithium dendrites easily precipitate on electrode sheets leading to poor cycle performance
Solution Approach 1:
The patent introduces a fluorinated cyclic carbonic ester additive as an intermediary substance in the electrolyte that mediates between lithium ions and the electrode surface. This additive preferentially decomposes to form a protective SEI film that acts as a barrier, preventing direct contact between lithium dendrites and the electrode sheet, thereby eliminating the harmful precipitation effect while maintaining battery operation
Solution Approach 2:
The patent modifies the electrolyte composition by incorporating fluorinated cyclic carbonic ester with specific molecular structure parameters (fluorine substitution, cyclic carbonate group). This parameter change in the electrolyte chemistry alters the decomposition behavior and SEI film properties, transforming the electrolyte's interaction with lithium dendrites from dendrite-promoting to dendrite-suppressing, thus improving cycle performance
2Power
If lithium dendrites precipitate on electrode sheets, then the battery can still function, but internal resistance increases and capacity decreases
Solution Approach 1:
The fluorinated cyclic carbonic ester additive performs preliminary action by decomposing first during initial charging cycles to form a stable SEI film on the electrode surface. This pre-formed protective layer prevents subsequent lithium dendrite precipitation that would otherwise increase internal resistance and reduce capacity, thereby preserving power performance throughout battery operation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The electrolyte additive reduces electrolyte and lithium metal loss, lowers battery resistance, and significantly improves cycle performance by forming a rigid and stable polymer layer that inhibits lithium dendrite growth.
Implementation Method 1
Dissolving a picric acid in an organic solvent to obtain an additive solution
Implementation Method 2
Performing crystallization from the additive solution, to precipitate the electrolyte additive
Implementation Method 3
the electrolyte additive can be polymerized to form BxOy (x=n, y=n+1) when a battery is charged and discharged, and at the same time, it is beneficial for an SEI film to generate
Implementation Method 4
The electrolyte added with the electrolyte additive can undergo an electropolymerization reaction during charging and discharging of the battery
Implementation Method 5
these substances can be preferentially adsorbed on the tips of lithium dendrites, which helps to make a polymer layer and the SEI film more rigid and stable, and helps to suppress the growth of the lithium dendrites
Data Source
AI summary
Disclosed are an electrolyte additive and a preparation method therefor, an electrolyte and a lithium ion battery. The preparation method for an electrolyte additive comprises: dissolving a picric acid in an organic solvent to obtain an additive solution, the organic solvent comprising at least one element of B, F and N; and performing crystallization from the additive solution, to precipitate an electrolyte additive. The electrolyte additive helps to make a polymer layer and an SEI film more rigid and stable, and helps to suppress the growth of lithium dendrites. The electrolyte added with the electrolyte additive can reduce the resistance of a lithium ion battery, and further improving the cycle performance of the lithium ion battery. The lithium ion battery provided in the present disclosure comprises the electrolyte added with the electrolyte additive, and therefore has a lower resistance and better cycle performance.